Yallourn mine

The Yallourn mine is owned by TRUenergy, a subsidiary of the CLP Group. The Yallourn West mine produces approximately 18 million tonnes of coal a year which is supplied to TRUenergy's Yallourn W power station.

On its website, the CLP Group states that the mine is "the second largest open-cut mine in Australia" which is "managed by a Roche Thiess Linfox (RTL) joint venture under an alliance contract with TRUenergy."

2007 mine wall collapse
On November 14, 2007 an 80-metre-high section of the wall at the Yallourn mine collapsed and slid 250 metres across the open-cut mine floor. The collapse resulted in approximately six million cubic metres of material obliterate a mine road and two major conveyor belts. The collapse led to a Mining Warden's investigation into the causes and appropriate responses. In his report, Professor Tim Sullivan was scathing about a series of errors which led to the final collapse. In his executive summary, Sullivan stated:


 * "The monitoring data shows the whole NE Batter was subject to large scale deep seated movements for a number of years prior to the collapse. The area of movement was of the order of four times or more larger than the eventual failure. The movements followed a long-term accelerating pattern and extensive experience shows that unless these movements ceased or were stabilised, failure was always likely to occur. There was also upward creep of the mine floor.


 * These movements, in about the last year and a half prior to the failure, caused disturbances to the existing groundwater regime around the NE Batter. These disturbances occurred within the batter itself in the coal and also extended to considerable depth below the coal in the interseam clays. These movements and disturbances were occurring well before the coal mining reached the final NE Batter.


 * In simple terms the historical experience in the Latrobe Valley coal mines had shown the critical technical components for mine batter stability were:
 * 1. Maintaining a low groundwater level in the coal seams, using horizontal bores.
 * 2. Ensuring low groundwater pressures in the aquifers and interseam clays below the mine floor and the batters. Traditionally this was carried out by deep aquifer dewatering.


 * Commencing around 2002, the documents indicate there was an effort to try and improve the overall efficiency of the mine, with questions raised over the need for routine horizontal bores, the requirement for continued deep aquifer dewatering and whether the monitoring and external engineering support could be reduced. Over time, studies and engineering modelling were carried out and some trials undertaken to assess some of these questions.


 * In about 2002 or 2003 following external evaluation and advice a decision was taken to stop routine drilling of horizontal bores. Although this evaluation was for the older part of the YEF, with different geotechnical conditions, somehow this decision also became applied to the NE Batter. Given the geotechnical conditions in the NE Batter, horizontal bores were always required and were critical for stability. The absence of horizontal bores was a major factor in the failure.


 * In 2004 following external assessment and advice from a number of different consultants, the deep aquifer dewatering bores in the mine floor were switched off and the bores were allowed to free flow under artesian conditions. The decision was also influenced by changes in the hydrogeological model in this part of the Yallourn Mine. The implications of these changes were not fully appreciated. The models used for assessing the impacts of cessation of deep aquifer dewatering were a simple weight balance model. The analyses centred around this model were focussed on rises in interseam pore pressures associated with rises in aquifer groundwater pressures. When significant rises did not occur the conclusion was drawn that there is no problem. However the impact of high, relative to the mine floor, and unchanging interseam pore pressures does not appear to have been appreciated."

Response to Sullivan report
Unions representing workers at the mine believe that the only reason no one was injured or killed was because the collapse occurred around 2a.m. in the morning.

Chris Fraser, the executive director of the Victorian Minerals Council complained that the government's response would impose additional costly burdens on the mining industry. "The recommendation for another layer of industry-wide regulation, funded by a new industry levy, should not be adopted by the Victorian Government. It is unnecessary and a disproportionate response," he stated in a media release. "It's a consultant's bonanza," he told The Age.

In another interview, Fraser complained that "the Government is preparing to establish a technical reference panel to review the geotechnical plans and activities of all mines. Mines will be forced to produce a technical report to the reference panel, which will undoubtedly add thousands of dollars in consultancy fees to each mine."

Related SourceWatch articles

 * Researching coal in Victoria
 * Victoria and coal


 * Australia and coal
 * Carbon Capture and Storage
 * Carbon Capture and Storage in Australia
 * New South Wales and coal
 * Queensland and coal

Photos of the 2007 mine wall collapse

 * Wayne Taylor, "Coal mine collapse", The Age, November 2007.

Victorian Government announcements

 * Peter Batchelor, Minister for Energy and Resources, "Government Announces Yallourn mine inquiries", Media Release, December 7, 2007.

TRUEnergy media releases on the Yallourn mine wall collapse

 * TRUenergy, "Subsidence reduces production at Yallourn mine", Media Release, November 14, 2007.
 * TRUenergy, "Works commence to restore Yallourn coal mine", Media Release, November 15, 2007.
 * TRUenergy, "Update on River Diversion and Generation Restoration at Yallourn", Media Release, November 22, 2007.
 * TRUenergy, "Yallourn mine operations fully restored", Media Release, March 18, 2008.

External articles

 * Shaun Malla, "Mi9ne Collapse", Latrobe Valley Express, November 15, 2007.
 * Heath Aston, "Workers spared in Victorian mine collapse after flood", Daily Telegraph, November 15, 2007.
 * "Yallourn mine inquiries commence: Two government inquiries have begun into last November's Yallourn mine collapse", Safety Solutions, January 15, 2008.